Overlaid LP-WUS and PDCCH Signaling for Low-Latency UE Wake-Up
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Solution Overview
Problem
Existing wireless communication systems face inefficiencies in power consumption, latency, and resource usage due to the use of low-power wake-up signals (LP-WUS) that require additional resources and cause latency when triggering physical downlink control channel (PDCCH) monitoring, especially in connected mode.
Innovation Solution
Implementing an orthogonal frequency division multiplexing (OFDM)-based control channel signal overlaid on low-power wake-up signals (LP-WUS) using on-off keying (OOK) modulation, allowing for joint transmission of PDCCH and LP-WUS, with OOK symbol durations aligned to OFDM symbol durations for efficient resource utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate PDCCH transmissions are used to trigger UE wake-up, then control information can be reliably transmitted, but processing power increases and latency increases
Solution Approach 1:
The patent combines the wake-up signal (WUS) and physical downlink control channel (PDCCH) into a single transmitted signal structure. The WUS uses OOK modulation while the PDCCH uses OFDM modulation, and both are transmitted simultaneously over the same time-frequency resources. This merging eliminates the need for separate transmissions, reducing latency while maintaining reliable control information delivery through the robust PDCCH component.
Solution Approach 2:
The transmitted signal serves multiple functions simultaneously: it acts as both a wake-up indicator (through the OOK-modulated WUS portion) and a control information carrier (through the OFDM-modulated PDCCH portion). This multi-functionality allows the system to trigger UE wake-up and deliver control information in a single transmission, improving efficiency without sacrificing reliability.
2Loss of information
If separate PDCCH transmissions are used, then control information is fully delivered, but resource usage increases
Solution Approach 1:
The patent merges WUS and PDCCH transmissions into a unified signal structure that occupies the same time-frequency resources. By combining these previously separate transmissions, the system delivers complete control information while reducing overall resource consumption, as the combined signal utilizes resources more efficiently than two separate transmissions would require.
3Use of energy by moving object
If LP-WUS with OOK modulation is used, then power consumption is reduced, but additional resources are required
Solution Approach 1:
The patent combines the low-power OOK-modulated WUS with the OFDM-modulated PDCCH into a single transmission. This merging allows the system to maintain the power-saving benefits of OOK modulation for the wake-up function while efficiently packing control information into the same resource allocation, thereby reducing total resource usage compared to separate transmissions.
Solution Approach 2:
The patent employs different modulation parameters for different signal components within the same transmission: OOK modulation for the WUS portion and OFDM modulation for the PDCCH portion. This parameter differentiation allows each component to be optimized for its specific function while sharing the same physical resources, achieving both power efficiency and resource efficiency.
Data Source
AI summary
Methods, systems, and devices for wireless communications are described that provide for a user equipment (UE) that operates in a low-power mode and monitors for a low power wake-up signal (LP-WUS) to indicate that the UE is to transition from the low-power mode to a higher power mode. The UE may receive an on-off keying (OOK) LP-WUS that has control information overlaid on one or more OOK ON symbols. The control information may be carried in a physical downlink control channel (PDCCH) that is provided as an orthogonal frequency division multiplexing (OFDM)-based control channel signal that is overlaid on an OOK LP-WUS. Within each OOK-ON symbol, an entire or partial PDCCH may transmitted, depending on the OOK symbol duration and number of information bits of the PDCCH.